Gasification questions....

[magnumhntr]

Well, I've been lurking here for quite a while, reading and comparing notes on what people are using, and/or recommending for an out of the house wood boiler. I was sold and hell bent on buying a Central Boiler this coming fall, but I am now researching the gasification boilers to buy instead. One thing I haven't been able to settle though, is this.

The one thing I was sold on for the OWB is the fact you can load it basically twice a day, and it regulates itself. So far everything I keep reading is that the gasification boilers want to runn full out to get maximum efficiency until they run out of fuel. Seeing as I am on a budget, the Garn is out of the question. Are there any gasification boilers that can go 10-12 hours on a loading of wood without a storage tank? I want a boiler that will heat my house and work shop reliably on 1 or 2 loadings a day. MAybe I'm missing something, but it seems the gasification units need a storage tank to be able to do this. Looking forward to any recommendations/comments.

Thank you!

Chris

 

[Eric Johnson]

Hi Chris. Welcome to the Boiler Room.

I'm running an EKO 60 without storage at the moment, and if I loaded full it twice a day, that would be more than enough for the relatively high heating load that I have (3,000 square feet of old house with a greenhouse is a pretty cold climate). Since I work from home part of the time and am around a lot, I tend to make smaller fires to keep the boiler from idling. But if I loaded it full first thing in the morning and then again in the evening, it would provide all our heat and hot water in all but the coldest weather. Storage is really nice, but it's not essential and it can always be added later.

Consider that a comparably-sized gasifier will burn half as much wood and do it with no smoke, and I think you can see the payback vector on a gasifier compared to any OWB. Worst case scenario: you burn more wood than you would with a tank, but still less than the CB, and do it with very little smoke.

 

[leaddog]

If you buy a gasification boiler and don't use storage have someone that KNOWS determine your heat load. You don't want to buy too big if you don't have storage. It will idle to much and you will have problems. They will work that way but that is why all the dealers talk about sizing them right. With storage you can fire them up twice a day or even Once a day if they are set up right. It just takes alittle longer to get them started from a cold start.
leaddog

 

[Seyiwmz]

Hi Chris, Well, I'm from the Upper Peninsula and have ran my Gasifier (EKO 40) for over 3 years without storage. I'm trying to install storage, but I can tell you what I have experienced without it. I have a propane gas boiler tied into my system and usually run the propane unit until mid-november. Then, run the EKO till about mid-March. The reason I don't start earlier or later is because I generate too much heat if I'm burning all day long. The boiler does idle, but even still it doesn't take much to overtemp when the outside temp is kinda warm. When I'm burning wood 24/7 I can get 10 to 12 hours on a load. Much of the time its idling. It's not the most efficient way to go, but it definately works. I want to install the storage to increase the efficiency and allow me to burn earlier and later in the year and give me some margin of error in the over temp department. I'm still learning myself, and appreciate the knowledge hanging around in this forum. I know I'm gonna need some help when it comes time to hook up my tank...... Seyiwmz

 

[Nofossil]

I'll second the suggestion that you want to get the smallest boiler that's big enough - that way, it doesn't idle as much. If you have a history of oil or gas bills, you can figure out your approximate fuel consumption per degree day, and from that you can get a good estimate of peak heat load. With or without storage, the smallest boiler that meets your peak heat load will be more efficient.

My $.02 on the topic of storage:

There's been a lot of talk about dramatic improvements in efficiency from using storage. I don't buy it. I think the improvement is more like 10%, and certainly not the 40% that's been suggested.

I'm heating 3500 square feet, well insulated but lots of glass. It's in Vermont, and I'm also heating domestic hot water and a hot tub. I use an EKO 25. First year, I didn't have storage. Second year, I did. I burned more wood the second year, though that's due to the fact that it was colder and I used the boiler for several more weeks.

The big advantage of storage is that you have some flexibility about when and how often you build fires, and the house temperature stays constant. My pattern with storage is one fire per day when it's cold. The fire averages about 7 hours. When it gets warmer I can skip days.

You can reload a gasifier with no problem. My small unit burns five hours on a full load. Without storage, it will go longer because it's idling some of the time.

 

[ISeeDeadBTUs]

Though my GreenWood does not have forced air induction, it claims to be a 'gassifier'. I've never used storage, though I anticipate doing so in the future. Mainly to integrate solar and eliminate the 'oil-man'. But also to eliminate 'idle' which will produce SOME smoke if there is wood fuel (not true with coals only) in the box.

Just my feeling, sizing is VERY important. When I almost bought a Central Boiler, the brochure indicated a smaller unit than the dealer did. Not sure who was correct, but I am guessing the dealer was just trying to get me to buy a BIGGER unit, so I could get LONGER burn times. Just one reason he didn't get my money ;-)

With the GW, I generally load 3 times a day, but it depends on
1) My schedule
2) Wind chill
3) what I load with

I have the smallest GW they make (100) and I am heating 4,000[] plus DHW. The next 48 hours will be a challenge for the GW, but storage would not help that. The few times it gets cold enough to cause me a little trouble are well worth the better efficiency of having the smaller unit. When it's a little warmer I find that it's still best to burn 3 loads a day, though at that point the loads are much smaller.

The refractory material of the GW is storage of sorts, and with a good coal bed pushed to the back and the door left closed, she will put out for quite a while when its 25+ outside. The trick seems to be knowing when and how to reload in order to get heat quickly while the box heats back up after an extended cycle.

Jimbo

 

[kuribo]

I'll second the suggestion that you want to get the smallest boiler that's big enough - that way, it doesn't idle as much. If you have a history of oil or gas bills, you can figure out your approximate fuel consumption per degree day, and from that you can get a good estimate of peak heat load. With or without storage, the smallest boiler that meets your peak heat load will be more efficient.

My $.02 on the topic of storage:

There's been a lot of talk about dramatic improvements in efficiency from using storage. I don't buy it. I think the improvement is more like 10%, and certainly not the 40% that's been suggested.

I think this is absolutely true....The main benefits of storage are two-fold: you can run the boiler full-out, which improves efficiency, and by storing heat, you can tailor your burns to be spaced farther apart (convenience). When you factor in the losses storage will add (heat, pumping, etc.), it may very well be the case that the main advantage of a storage system is more about convenience than efficiency increases....

 

[magnumhntr]

Thanks guys! This is the info I was hoping for! I have a brand new 1800 sq ft cape cod style house with a lot of windows, a walk out basement, and a 600 sq ft insulated garage. Plus I will be looking to heat 6-700 sq ft of insulated workshop in a pole barn, and my domestic hot water. Heating in the house is a forced air unit (heat exchanger is already installed), and will use a forced air exchanger in the pole barn and garage. What would be your recommendations for a good, reliable gasifier? Also, for those that heat without storage, how much do they smoke at idle, and when coming off idle? Is it as bad as a OWB, or slightly more than when it's running wide open?

Thanks again!

Chris

 

[Nofossil]

Thanks guys! This is the info I was hoping for! I have a brand new 1800 sq ft cape cod style house with a lot of windows, a walk out basement, and a 600 sq ft insulated garage. Plus I will be looking to heat 6-700 sq ft of insulated workshop in a pole barn, and my domestic hot water. Heating in the house is a forced air unit (heat exchanger is already installed), and will use a forced air exchanger in the pole barn and garage. What would be your recommendations for a good, reliable gasifier? Also, for those that heat without storage, how much do they smoke at idle, and when coming off idle? Is it as bad as a OWB, or slightly more than when it's running wide open?

Thanks again!

Chris

I ran my EKO 25 for a year without storage, and it idles briefly from time to time even now. As long as you have dry wood, it's barely noticeable unless it's been idling a very long time. Much less smoke than a conventional boiler even coming off idle.

 

[Eric Johnson]

The worst smoke you get out of a gasifier, IME, is far less than what you see from an OWB. Usually there's no smoke at all. Coming off of idle it cleans up almost immediately. That's when the blowers kick back on and gasification resumes.

 

[magnumhntr]

Another question on the gasifiers....

I saw something about these being closed units in another thread. Is this true of the EKO's and Tarms? I take it closed is being pressurized? If this is so, what are the safeties if it overheats? Is it like a hot water heater where there is a safety valve? And if it were to overboil, do they have a water level indicator so you know when/how much filling it needs? And do they have the potential to burst within the home of piped in from outside? Trying to get a better idea how these operate vs an open system OWB.

Thanks!

Chris

 

[Reggie Dunlap]

Yes they are pressurized boilers. My Tarm runs at around 15 PSI at 190 degrees. It has a pressure relief valve that will open at 30 PSI, which should be around 230 degrees. It's important to have a gravity fed loop so in case you lose power.

Improperly installed I'm sure a boiler could blow up. I always open pressure relief valves every year or so to make sure they work right.

 

[Eric Johnson]

There's really no difference between a regular gas or oil boiler and a gasifier, or other indoor boiler for that matter. Most are pressurized, have pressure relief valves, expansion tanks, air scoops, etc. And no more or less dangerous than a regular fossil fuel boiler if installed and operated correctly.

 

[Nofossil]

And no more or less dangerous than a regular fossil fuel boiler if installed and operated correctly.

I like to think of them as nofossil fuel boilers ;-)

 

[SE Iowa]

What is the the typical size of the storage tanks? Are they just poly tanks in your basement or what?

 

[Nofossil]

What is the the typical size of the storage tanks? Are they just poly tanks in your basement or what?

Scan the tank-related threads - there's a bit of everything. A reasonable rule of thumb is that you'd like enough storage so that you can run the boiler flat out for a few hours, then live off the tank until the next day. Requires some calculations based on your heat load, but tanks seem to range from 500 to 1500 gallons. Unlike boiler capacity, more is generally better.

Tanks have to be steel or some strong structure with EPDM lining. Poly won't take the heat.

My site (link in signature below) describes my storage scheme. There are many other ways of doing it.